package String;

public class ToUpCaseDemo {
    public static void main(String[] args) {
        String s1="我爱Java!";
        String s2=s1.toUpperCase();
        String s3=s1.toLowerCase();
        System.out.println(s1);
        System.out.println(s2);
        System.out.println(s3);
    }
}
